246.Strobogrammatic Number

1-HashTable

class Solution {
    public boolean isStrobogrammatic(String num) {
        Map<Character, Character> map = new HashMap<>();
        map.put('0', '0');
        map.put('1', '1');
        map.put('6', '9');
        map.put('8', '8');
        map.put('9', '6');
        char[] tmp = num.toCharArray();
        for(int i = 0, j = tmp.length - 1; i <= (tmp.length - 1) / 2; i++, j--){
            if(!map.containsKey(tmp[i]) || !map.containsKey(tmp[j]))
                return false;
            if(map.get(tmp[i]) != tmp[j])
                return false;
            char c1 = map.get(tmp[j]);
            char c2 = map.get(tmp[i]);
            tmp[i] = c1;
            tmp[j] = c2;
        }
        return true;
    }
}